Electrolytic rheostat



April 10, 1951 v. H. SMITH ELECTROLYTIC RHEOSTAT Filed May 18, 1950 M 6 R nM mm a ,H m

Patented Apr. 10, 1951 UNITED STATES PATENT OFFICE 9 Claims.

This invention pertains to improvements in electrical control mechanisms, and is particularly directed to improvements in electrolytic rheostats.

One of the objects of this invention is to provide a rheostat control mechanism of high sensitivity and accuracy of control over a wide range of speeds for a motor to be controlled by the mechanism.

Still another object of this invention is to provide an improved electrolytic rheostat capable of sensitive and fine adjustments for regulating the speed of an operating motor controlled by the rheostat.

Another object of this invention is to provide a speed variation control rheostat for a motor utilizing an electrolyte and adjusting a pair of electrodes in the electrolyte to effect a speed variation control for an electric motor connected to said rheostat.

Another object of this invention is to provide an improved electrolytic rheostat for an alternating current sewing machine motor.

It is also an object of this invention to provide an improved electrolytic rheostat in which the electrolyte is contained in a completely enclosed chamber and in which one of the electrodes is movable relative to the other electrode from a position removed from the electrolyte, through the electrolyte, to a position of direct contact with the other electrode.

Further features and advantages of this invention will appear from a detailed description of the drawings in which:

Figure 1 is a plan view of an electrolytic rheostat incorporating the features of this invention.

Figure 2' is a vertical transverse section through the rheostat indicated by the line 2-2 in Figure 1.

Figure 3 is an enlarged fragmentary sectional view on the line 33 of Figure 1.

As exemplary of one embodiment of this invention there is shown a structure comprising a tank I composed of suitable insulative material which may be of any well known plastic substance such as Bakelite, or the like in which is contained a dilute solution I I of sodium chloride or calcium chloride tb form an electric conducting solution of relatively high resistance. The solution is maintained at a level [2 in the tank Ill. The tank is totally enclosed by means of a cover l3 also of suitable insulative material in which is carried one fixed electrode I 4 held in place by suitable nuts and washers I5. One

power supply line LI is connected to the electrode [4 by a suitable binding post 16.

Movably mounted in the tank IE] is the second electrode H which is supported on a rocking yolk piece l8 having trunnions I9 journaled in suitable bearings 28 formed in the cover member 13 and opening into a bore 2| also formed in the cover member l3. Directly above the rocking yolk piece l8, as best seen in Figure 3, is a flexible diaphragm of suitable insulative material 2:2 which is secured to the top surface 23 of the cover member l3 by the clamp plate 24 and appropriate screws 25 so as to form a liquid tight seal between the surface 23 and the flexible diaphragm 22. The clamp plate 24 is provided with a bore 26 of similar size to the bore 21 in the cover member I3.

The electrode [1 projects upwardly through the yolk member [8 through the diaphragm 22 and is rigidly locked together with both of these members by means of suitable washers and nuts 21. The electrode I! therefore rocks about the axis of the trunnions l9 While at the same time the chamber 28 within the tank It] is sealed oil through the flexible diaphragm 22 for any position of movement of the electrode H. The other power supply line L2 is suitably connected to the electrode I! by means of a suitable binding post 29 mounted on the outer end of the movable elec trode IT.

The electrode I1 is so constructed and bent at 30 that it normally lies in a horizontal position Ha completely removed from the electrolyte ll in the tank member Ill and it may swing to in termediate position such as position llb or to fully open position of no resistance of current flow from Ll to L2 such as at [10. In position lie the electrode I! may directly contact the electrode M at the point 3| with both electrodes fully submerged in the electrolyte ll.

Normally, the electrode I! is held in the biased disconnect position Ila by means of the tension spring 32 which is connected to the electrode I! by means of the piece 33 secured to it by a suitable nut 34 below the binding post 29, the other end of the spring being connected by a suitable link or hook piece 35 rigidly secured to the tank I 0. The piece 33 is connected through suitable links 36 and 3'! interconnected by means of an insulative link 38 to the lever arm 39 of the knee actuating lever 40 pivotally mounted on a suitable pin 4| carried in a suitable manner, as by a bracket 42 on the tank member iii. A stop pin 43 located in rigid position relative to the tank member l0 engages the edge 44 of the lever arm 39 so as to limit the normal stop position by the spring 32 of the electrode ll to the position He shown in Figure 2. A curved knee engaging portion 400/, may be provided on the lever 3B for ready operation of the rheostat by the operator of a sewing machine or any other machine being driven by a motor energized through the rheostat.

The solution H in the tank member it is normally hermetically sealed off in the tank it by means of a suitable rubber cork or closure cap i5 which may contain a microscopic vent hole 16 to allow for contraction and expansion of the liquid II and gas pressure or air in the chamber 28. The opening G6 may be of such small size however that the liquid I i cannot escape therethrough though the gas in the chamber 28 may be readily vented through the cork 45.

With the lines LI and L2 connected in series with one power supply line of a source of power and with one terminal of an electric motor or other device to be controlled, the switch may be operated from a no current flow position of the control lever 40 as shown at Mic with the electrode I! in the position Ha to engage the electrode ll with the solution I l in varying degrees. At various intermediate positions ill) the motor or device may be energized more or less to effect its speed of operation with an extreme nicety and preciseness of speed regulation being obtained. Finally as greater and greater speeds are desired as in moving the control lever from position dfib down to position Mic, the electrode ll is finally brought into direct contact with the electrode is at the point It! to give full voltage nonresistance connection through the rheostat from lines L! to L2 for maximum power and full speed operation of the machine being controlled. It is to be further noted that in this arrangement the initial stages of contact between position lid and llb of the electrode l l with the surface l2 of the solution I l takes place at a greater rate and sensitivity than relative movement from position ill) to I10. This results in excellent low speed range control for the device connected to be controlled by this improved electrolytic rheostat.

Having thus fully described this invention and its numerous attendant advantages, it is obvious that many changes may be made in the form, construction and arrangement of the parts without departing from the spirit or scope of the invention or sacrificing its attendant advantages, the form herein described being a preferred embodiment for purposes of exemplifying this invention.

What is claimed is:

1. An electrolytic rheostat comprising a tank, a cover fixed on said tank, an electrolyte in said tank, a fixed electrode supported from said cover in said tank submerged in said electrolyte, a movable electrode, means for mounting said movable electrode on said cover, and means for actuating said movable electrode from a position above the electrolyte in said tank to intermediate positions of partial submergence in said electrolyte.

2. An electrolytic rheostat comprising a tank, an electrolyte in said tank, a fixed electrode in said tank submerged in said electrolyte, a movable electrode, means for mounting said movable electrode on said tank, and means for actuating said movable electrode from a position above the electrolyte in said tank to intermediate positions of partial submergence in said electrolyte, and

finally to a position of maximum submergence and direct contact with said fixed electrode.

3. In an electrolytic control rheostat having a tank containing a fluid electrolyte, a fixed electrode submerged in said electrolyte and rigidly mounted on said tank, a movable electrode, means for movably mounting said movable electrode on said tank, yielding means for normally holding said movable electrode in a disconnected position out of said electrolyte, and an operating lever connected to said movable electrode to move it into and through said electrolyte.

4. In an electrolytic control rheostat having a tank containing a fiuid electrolyte, a fixed electrode submerged in said electrolyte and rigidly mounted on said tank, a movable electrode, means for movably mounting said movable electrode on said tank, yielding means for normally holding said movable electrode in a disconnected position out of said electrolyte, and an operating lever connected to said movable electrode to move it into and through said electrolyte to a position of engagement with said fixed electrode.

5. In an electrolytic rheostat having a tank containing fiuid electrolyte, a fixed electrode submerged in said electrolyte, a movable electrode, means for movably mounting said movable electrode on said tank comprising a trunnion member pivotally journaled on said tank, a flexible diaphragm secured to said tank, and means securing said movable electrode, trunnion member, and said diaphragm rigidly together to provide support for said movable electrode on said tank.

6. In an electrolytic rheostat having a tank containing fluid electrolyte, a fixed electrode submerged in said electrolyte, a movable electrode, means for movably mounting said movable electrode on said tank comprising a trunnion member pivotally journaled on said tank, a fiexible diaphragm secured to said tank, and means securing said movable electrode, trunnion member, and said diaphragm rigidly together to provide support for said movable electrode on said tank, bias spring means connected to said movable electrode to normally yieldingly hold said movable electrode in a disconnected position out of said electrolyte, and an actuating lever pivotally mounted relative to said tank and connected by linkage means to said movable electrode for moving said movable electrode into and through said electrolyte and into engagement with said fixed electrode.

7. In an electrolytic rheostat having a tank, an electrolyte in said tank, electrodes in said tank movable relative to each other in said electrolyte, and means for sealing said tank comprising a resilient plastic cork or the like having a microscopic vent therein secured in an accessopening of said tank.

8. In an electrolytic rheostat structure having a tank, an electrolyte in said tank, a fixed electrode having a horizontal member located in said electrolyte near the bottom of said tank, a movable electrode pivotally mounted at the top of said tank having a member normally held in horizontal position at the top of said tank and above said electrolyte, and means for pivotally actuating said movable electrode to swing its outer end downwardly through said electrolyte relative to the horizontal member of said fixed electrode.

9. In an electrolytic rheostat structure having a tank, an electrolyte in said tank, a fixed electrode having a horizontal member located in said electrolyte near the bottom of said tank, a mov- 5 6 able electrode pivotally mounted at the top of REFERENCES CITED Sam tank havmg member normally held m The following references are of record in the horizontal position at the top of said tank and file of this patent: above said electrolyte, and means for pivotally actuating said movable electrode to swing its 5 UNITED STATES PATENTS outer end downwardly through said electrolyte Number Name Date relative to the horizontal member of said fixed 475,255 Sterling May 17, 1892 electrode and finally into direct contact with said horizontal member of said fixed electrode. FOREIGN PATENTS 0 Number Country Date VICTOR H. SMITH. 705,360 France June 16, 1931 

